It’s really not a simple question to answer as it involves knowing some specifics. If you can settle on the actual products you wish to use you can calculate their hourly power usage and multiply by how many hours you expect to use each item. Once you’re confident you’ve got everything it’s probably smart to add a little extra for unforseen power usage. There’s a few websites out there with calculators set up for this. I think Faroutride.com has a good one